Sir Thomas Armstrong (15 June 1898 – 26 June 1994) was an English organist, conductor, composer, educationalist and adjudicator. He had a substantial influence on British music for well over half a century. From 1955 to 1968 he was principal of the Royal Academy of Music. He was knighted in 1958 for his services to music.
Thomas Henry Wait Armstrong was born in Peterborough, the son of A.E. Armstrong, music teacher, organist of St. Augustine's Church, Woodston, and conductor of the local orchestra and operatic society. Thomas became a choirboy at the Chapel Royal, St James's Palace from 1907 to 1910 where he sang at the funeral of King Edward VII in Westminster Abbey in 1910. From 1911 to 1915 he attended The King's School, Peterborough. During this time he took lessons from his father and practised on the organ at Woodston every day before school, paying a boy a shilling each time for pumping the bellows. After a short period as organist of Thorney Abbey he became articled to Haydn Keeton, organist of Peterborough Cathedral. His fellow apprentice was Malcolm Sargent, the future conductor, who became a lifelong friend. James Blades, the future percussionist, was a chorister there at the time. Armstrong served as assistant organist in Peterborough for a year before being elected organ scholar of Keble College, Oxford in 1916.
His studies were interrupted by service in France during World War I. After the war he completed his studies in Oxford, studying music with Professor Sir Hugh Allen and organ under Dr Henry Ley at Christ Church. After going down from Oxford in 1922 he briefly took up an appointment at Manchester Cathedral (assistant organist), during which time he worked with Sir Hamilton Harty. The following year he was appointed organist of St. Peter's Church, Eaton Square, London. During this period he studied at the Royal College of Music with Holst and Vaughan Williams, the latter becoming a lifelong friend. During this time he played the piano in cinemas for silent films, thus developing his skills as an improviser. From 1928–1933 he was organist of Exeter Cathedral. During this period he was Director of Music of University College of the South-West. In 1929 he was awarded the Oxford DMus. He returned to Oxford in 1933 as organist of Christ Church in succession to William Harris who had been appointed to St George's Chapel, Windsor. Armstrong immersed himself in the musical life of the town, teaching, examining and conducting the Oxford Bach Choir and Orchestral Society. His career reached a highlight in 1955 when he was appointed Principal of the Royal Academy of Music, a post from which he retired in 1968.